The invention relates to a device for achieving a uniform distribution of the gas flowing radially through a catalyst bed in a reactor for catalytic reactions. The device comprises an annular catalyst basket with gas-permeable cylindrical walls, a gastight bottom, and a gastight cover. The catalyst basket is arranged in an annular vessel having a gastight bottom, an outer wall and a shorter inner wall so as to obtain an outer annular space for the influence of fresh gas and an inner annular space for the effluent reaction gas which passes over the shorter inner wall. Catalyst beds for such radial gas flow are specifically suitable for reactors in industrial plants, e.g. ammonia synthesis plants, because due to the low pressure drops, substantial energy can be saved in process gas recycling.
Such catalyst beds require a uniform gas flow across their entire height. Otherwise, different velocities of gas flow will occur involving irregularities in the reaction.
According to German Pat. 15 42 499, a design was proposed for the gas inlet wall which would induce a pressure drop by using two parallel faces provided with a multitude of different openings.
The design of the gas inlet wall for the catalyst bed, as suggested in the German Pat. 15 42 499, was such that by arranging for two parallel faces being provided with a multitude of different openings, a pressure drop was achieved which was substantially superior to that across the catalyst bed. In this case, provision was made for a multitude of holes to serve as restriction orifices.
According to German Pat. 20 19 706, the design for achieving a uniform gas distribution in catalysts through which the gas flows radially from the center toward the periphery graduates the cross-sections of the gas passage openings in the inner gas distribution pipe as a function of the height of the catalyst bed. The openings in the outer cylindrical plates of the catalyst basket are uniformly distributed over the entire plate and have an area being at least as large as the area of the openings in the first fourth of the inner cylindrical plate of the catalyst basket. In this case, a uniform distribution of the gas over the entire height of the catalyst bed is not obtained by an increased pressure drop across restriction orifices, but by a special arrangement of openings of different cross-sections.